Limin Xing

CD8+HLA-DR+ T cells are increased in patients with severe aplastic anemia

The aim of the present study was to investigate the number and function of CD8+HLA-DR+ cells, which are considered to be activated cytotoxic T lymphocytes (CTLs), in peripheral blood to further examine the pathogenesis of severe aplastic anemia (SAA). Thirty-eight patients with SAA were included in the present study. Patients were screened for paroxysmal nocturnal hemoglobinuria by flow cytometry using anti-CD55 and anti-CD59 antibodies. The number of CD8+HLA-DR+ T cells was measured by three-color flow cytometry using anti-CD8-peridinin chlorophyll, anti-CD3-fluorescein isothiocyanate (FITC) and anti-HLA-DR-FITC antibodies. The expression of perforin, granzyme B, tumor necrosis factor-β (TNF-β) and FasL in CD8+HLA-DR+ T cells was detected by flow cytometry with the appropriate monoclonal antibodies. Total RNA was prepared from purified CD8+HLA-DR+ cells of healthy controls and SAA patients, and then polymerase chain reaction (PCR) was performed. Apoptosis of CD8+HLA-DR+ cells was detected by flow cytometry following staining with Annexin V. The proportion of CD8+HLA-DR+ T cells was analyzed by flow cytometry in peripheral blood and was identified to be significantly higher in untreated SAA than in remission patients and in the controls. The expression of perforin, granzyme B, TNF-β and FasL in CD8+HLA-DR+ T cells was analyzed by flow cytometry and PCR, which revealed increased expression in the untreated SAA group compared with that in the control group. Furthermore, the apoptosis of CD3- bone marrow cells from normal individuals was enhanced following co-culture with CD8+HLA-DR+ T cells from untreated SAA patients. In conclusion, the present study demonstrated that CD8+HLA-DR+ T cells may contribute to bone marrow failure in SAA.

Granulocyte transfusion combined with granulocyte colony stimulating factor in severe infection patients with severe aplastic anemia: a single center experience from China.

Objective To investigate the efficacy and safety of granulocyte transfusion combined with granulocyte colony stimulating factor (G-CSF) in severe infection patients with severe aplastic anemia (SAA). Methods Fifty-six patients in severe infections with SAA who had received granulocyte transfusions combined with G-CSF from 2006 to 2012 in our department were analyzed. A retrospective analysis was undertaken to investigate the survival rates (at 30 days, 90 days and 180 days), the responses to treatment (at 7 days and 30 days, including microbiological, radiographic and clinical responses), the neutrophil count and adverse events after transfusion. Results All SAA patients with severe infections were treated with granulocyte transfusions combined with G-CSF. Forty-seven patients had received antithymocyte globulin/antilymphocyte globulin and cyclosporine A as immunosuppressive therapy. The median number of granulocyte components transfused was 18 (range, 3–75). The survival at 30 days, 90 days and 180 days were 50(89%), 39(70%) and 37(66%) respectively. Among 31 patients who had invasive fungal infections, the survival at 30 days, 90 days and 180 days were 27(87%), 18(58%) and 16(52%) respectively. Among the 25 patients who had refractory severe bacterial infections, the survival at 30 days, 90 days and 180 days were 23(92%), 21(84%) and 21(84%) respectively. Survival rate was correlated with hematopoietic recovery. Responses of patients at 7 and 30 days were correlated with survival rate. Common adverse effects of granulocyte transfusion included mild to moderate fever, chills, allergy and dyspnea. Conclusion Granulocyte transfusions combined with G-CSF could be an adjunctive therapy for treating severe infections of patients with SAA.

Essential role for histone deacetylase 11 (HDAC11) in neutrophil biology

Epigenetic changes in chromatin structure have been recently associated with the deregulated expression of critical genes in normal and malignant processes. HDAC11, the newest member of the HDAC family of enzymes, functions as a negative regulator of IL‐10 expression in APCs, as previously described by our lab. However, at the present time, its role in other hematopoietic cells, specifically in neutrophils, has not been fully explored. In this report, for the first time, we present a novel physiologic role for HDAC11 as a multifaceted regulator of neutrophils. Thus far, we have been able to demonstrate a lineage‐restricted overexpression of HDAC11 in neutrophils and committed neutrophil precursors (promyelocytes). Additionally, we show that HDAC11 appears to associate with the transcription machinery, possibly regulating the expression of inflammatory and migratory genes in neutrophils. Given the prevalence of neutrophils in the peripheral circulation and their central role in the first line of defense, our results highlight a unique and novel role for HDAC11. With the consideration of the emergence of new, selective HDAC11 inhibitors, we believe that our findings will have significant implications in a wide range of diseases spanning malignancies, autoimmunity, and inflammation.

The Clinical and Immune Characteristics of Patients with Hepatitis-Associated Aplastic Anemia in China

Hepatitis-associated aplastic anemia (HAAA) is a variant of severe aplastic anemia (SAA) in which bone marrow failure follows an acute attack of hepatitis. Its pathogenesis is poorly understood. We investigated the prevalence of HAAA among cases of newly diagnosed SAA presenting to our hospital between January 1998 and February 2013, and analyzed the clinical and immune characteristics of HAAA and non-hepatitis-associated SAA (non-HASAA) patients. The prevalence of HAAA among cases of SAA was 3.8% (36/949), and the majority of patients (33/36) were seronegative for a known hepatitis virus. Compared with non-HASAA patients, HAAA patients had a larger proportion of CD8+ T cells, a lower ratio of CD4+/CD8+ T cells, and a smaller proportion of CD4+CD25+ regulatory T cells. There was no significant difference in peripheral blood count, bone marrow cellularity, or the number of blood transfusions received between HAAA and non-HASAA patients. HAAA patients had a higher early infection rate and more infection-related mortality in the first 2 years after diagnosis than non-HASAA patients, and their 2-year survival rate was lower. The results demonstrate that HAAA patients have a more severe T cell imbalance and a poorer prognosis than non-HASAA patients.

Abnormalities of quantities and functions of natural killer cells in severe aplastic anemia

Severe aplastic anemia (SAA) is a rare disease characterized by severe pancytopenia and bone marrow failure. Natural killer (NK) cells are large granular lymphocytes derived from hematopoietic stem cells (HSCs) or common lymphoid progenitors (CLP). They play a key role in n the innate immunity and adaptive immune. In this study, the quantitative and functional changes of natural killer (NK) cell subsets in peripheral blood of severe aplastic anemia (SAA) patients before and after immunosuppressive therapy (IST) were investigated. Results showed that the percentage of NK cells and its subsets in peripheral blood lymphocytes was decreased in SAA patients. After IST, the percentage of NK cells and their subsets increased dramatically. The median expressions of CD158a, NKG2D and NKp46 on NK cells were higher in SAA patients compared to that in normal controls, and the expressions of perforin in newly diagnosed and recovery SAA patients were higher than that in controls. Therefore, we concluded that the decrease of total NK cells, and CD56bright, CD56dim NK cell subsets and the higher expressions of NKp46 and perforin on NK cells may cause the over-function of T lymphocytes and thus lead to hematopoiesis failure in SAA.

Elevated TIM3+ hematopoietic stem cells in untreated myelodysplastic syndrome displayed aberrant differentiation, overproliferation and decreased apoptosis

TIM3, as a negative regulator of anti-tumor immunity, is highly expressed on LSCs, but not on normal HSCs. TIM3 on HSCs in MDS patients has not been clarified. Here, both the percentage of TIM3 on HSCs and the MFI of TIM3+ HSCs were higher in untreated MDS than control and were closed to AML, and excessive TIM3+ HSCs was closely related to clinical parameters: WPSS score, karyotype analysis, morphologic blasts, the number of cytopenia involving hematopoietic lineages, anemia and granulocytopenia. TIM3+ HSCs expressed lower CD11b, TpoR, EpoR, G-CSFR and Annexin V, and higher CD71 and GATA2. TIM3+ HSCs displayed aberrant differentiation, overproliferation and decreased apoptosis. TIM3 might be a promising marker for identifying malignant clone cells in MDS and a candidate for targeted therapy.

Abnormalities of quantities and functions of linker for activations of T cells in severe aplastic anemia

Severe aplastic anemia (SAA) is a rare immune‐regulated disease characterized by severe pancytopenia and bone marrow failure, caused by destruction of hematopoietic cells by the activated T lymphocytes. Linker for activation of T cells (LAT), a transmembrane adaptor protein, plays a key role in T‐cell and mast cell functions. However, it remains unclear how LAT may change in patients with SAA. This study aims at understanding the role of lymphocyte LAT in SAA.

TET2 Expression in Bone Marrow Mononuclear Cells of Patients with Myelodysplastic Syndromes and Its Clinical Significances

Objective To investigate the expression of TET2 mRNA and protein in the bone marrow mononuclear cells (BMMNC) of patients with myelodysplastic syndrome (MDS) and its clinical significance. Methods The expression of TET2 mRNA and protein in bone marrow mononuclear cells (BMMNC) of 32 patients with MDS and 20 healthy donors was examined by qPCR and Western blot. Results The expression of TET2 mRNA in BMMNC was down-regulated in MDS patients compared with the donor group [(0.41±0.28)% vs. (1.07±0.56)%] (P<0.001). Compared with lower expression group (TET2<0.4) [(6.53±6.17)%], patients with higher expression of TET2 (≥0.4) presented significantly lower proportion of bone marrow blasts [(1.21±1.56)%] (P<0.05). The expression of TET2 mRNA in BMMNC of MDS patients was inversely correlated with malignant clone burden (r=-0.398, P<0.05) and IPSS (r=-0.412, P<0.05). The expression of TET2 protein was down-regulated in MDS patients compared with that in the donor group. Conclusions The mRNA and protein expression of TET2 in BMMNC of MDS patients is decreased, which might be useful as an important parameter for the evaluation of MDS clone burden.

Recombinant Human Thrombopoietin Treatment Promotes Hematopoiesis Recovery in Patients with Severe Aplastic Anemia Receiving Immunosuppressive Therapy

Objective. To assess the effectiveness of recombinant human thrombopoietin (rhTPO) in severe aplastic anemia (SAA) patients receiving immunosuppressive therapy (IST). Methods. Eighty-eight SAA patients receiving IST from January 2007 to December 2012 were included in this retrospective analysis. Of these, 40 subjects received rhTPO treatment (15000 U, subcutaneously, three times a week). rhTPO treatment was discontinued when the platelet count returned to normal range. Hematologic response, bone marrow megakaryocyte recovery, and time to transfusion independence were compared. Results. Hematologic response was achieved in 42.5%, 62.5%, and 67.5% of patients receiving rhTPO and 22.9%, 41.6%, and 47.9% of patients not receiving rhTPO at 3, 6, and 9 months after treatment, respectively (P = 0.0665, P = 0.0579, and P = 0.0847, resp.). Subjects receiving rhTPO presented an elevated number of megakaryocytes at 3, 6, and 9 months when compared with those without treatment (P = 0.025, P = 0.021, and P = 0.011, resp.). The time to platelet and red blood cell transfusion independence was shorter in patients who received rhTPO than in those without rhTPO treatment. Overall survival rate presented no differences between the two groups. Conclusion. rhTPO could improve hematologic response and promote bone marrow recovery in SAA patients receiving IST.

Expression of DLK1 Gene in the Bone Marrow Cells of Patients with Myelodysplastic Syndromes and Its Clinical Significance

Objective This study aims to investigate the expression of delta-like 1 (DLK1) gene in the bone marrow cells of patients with myelodysplastic syndromes (MDS) and to explore its molecular characteristics for the early diagnosis of MDS. Methods The expression of DLK1 mRNA in the bone marrow cells of cases with MDS, acute myeloid leukemia (AML), and normal control groups were measured by real-time polymerase chain reaction and were analyzed for clinical significance. Results Significantly higher expression of DLK1 mRNA was observed in the bone marrow cells of MDS patients (0.7342±0.3652) compared with the normal control group (0.4801±0.1759) (P<0.05). The expression of DLK1 mRNA had a positive correlation with the proportion of bone marrow blasts (r=0.467, P<0.05). Moreover, DLK1 mRNA expression was significantly increased as MDS progressed (P<0.05). Patients with abnormal karyotypes exhibited significantly higher expression of DLK1 mRNA (0.9007±0.4334) than those with normal karyotypes (0.6411±0.2630) (P<0.05). Subsequently, patients with highly expressed DLK1 (≥0.8) presented significantly higher malignant clone burden (0.4134±0.3999) than those with lower DLK1 expression (<0.8),(0.1517±0.3109), (P<0.05). Conclusions The DLK1 gene was highly expressed in MDS patients, and was increased as MDS progressed. The expression of DLK1 mRNA was positively correlated with the proportion of the bone marrow blasts. A high expression of DLK1 gene suggested a higher malignant clone burden of MDS.